Battery issue

Mine has a sheet alloy battery holder. Battery is retained by a rubber band.  Just like the fuel tank.  Photo tomorrow if it's any help.

My old friend used a smaller modern battery to leave room for a small tool roll underneath.  Al O of this parish has strong views on not using too small a battery if you choose to use an AGM type.  Otherwise they will boil dry.

The  99 DL uses a clever steel clamp at the base of the battery so the height of the battery is not an issue. I have added a leather ( Jacko skate) strap over the battery which also clamps my EI box to the face of the battery . Happily the whole messy gubbins ( along with all sorts of extra   frippary)  is hidden by those clever tin  panels  just  like a modern bike But years before its time.

I used a battery clamp from Halfords and modified it suit.

Drilled some new holes and shortened the top bar, then cut the screwed rods shorter and re- threaded them - I think it was M5 or 6.  I bent the curved bottom bits a little more too.  It works a treat and uses the original holes in the battery box.

Be carfull if using the above battery clamp-should the clamp short the battery-you burst into flames!! But a piece of wood under the battery is a good idea-it soaks up any acid spils, easily replaced, absorbs vibration, easily cut to size. ANY battery less than 5 ahr will in time over charge. Sealed batteries (spade terminals) from the Alarm world will over charge-dry out. If you use them, you 'get away with it' Your choice.

This is mine.  Made for Yuasa.  Green stuff is camping mat.

I would never use any kind of rubber or flexible retainer for a battery.  Rubber can give way and perish. On a car the rigid battery clamps are supposed to be checked at MoT time.  In the Olden Days there used to be rubberised paint to treat the interior of the battery box.

I replaced it once in 23 years.

I protect the box from acid with a brushed on coat of Waxoil, fit a long breather pipe and secure the battery well. . I take the battery out every couple of months to check level ,and charge ,A desulphator gaget connected when charging  turns a 10 year old  battery that looses interest at 13 volts into a 14.4 volt powerhouse . 

Have 3 bikes with rubber bands, two Victor Specials and a CB250 racer. Though I had to replace the band on one BSA after 53 years of service. Rubber vibration insulation was a good idea back in the days. Maybe modern batteries can withstand more vibrations.

... and elastic bands (usually bits of old inner tube) are my regular solution to battery location as on my current Tri-Greeves project:

Following the recent discussion on securing the battery in a featherbed battery box, this is my solution:  Using M6 threaded studding I either used existing holes in the back of the housing or drilled new holes at a suitable height and fixed these in place with two nuts to lock them to the casing.  To stop the battery rubbing the studding I slid over some plastic tube. 

The securing bar was from some spare aluminium off cut and this drilled to suit the studs and some foam rubber was stuck onto the back of it.  Wing nuts are used to hold this bar in place.

A thick piece of rubber was used under the battery, with holes cut out where the battery box mounting bolts stick up in the base of the housing.

This holds the battery securely and makes it easy to remove the battery.